LT1912 Linear Technology Corporation, LT1912 Datasheet
LT1912
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LT1912 Summary of contents
Page 1
... Q cuitry. Current mode topology is used for fast transient response and good loop stability. The LT1912 allows the use of ceramic capacitors resulting in low output ripple while keeping total solution size to a minimum. The low current shutdown mode reduces input supply current to less than 1μ ...
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... V = 10V CONDITIONS V = 0.2V RUN/ 3V, Not Switching Not Switching 0.2V RUN/ 3V, Not Switching Not Switching BD LT1912E ........................................... –40°C to 125°C TOP VIEW BOOST N/C IN RUN/ ...
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... Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT1912E is guaranteed to meet performance specifi cations from 0°C to 125°C. Specifi cations over the –40°C to 125°C operating The denotes the specifi ...
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... LT1912 TYPICAL PERFOR A CE CHARACTERISTICS Effi ciency 100 V = 12V 34V 24V IN 70 www.DataSheet4U.com www.DataSheet4U.com 60 L: NEC PLC-0745-5R6 500kHz OUT 50 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 LOAD CURRENT (A) Maximum Load Current 3.5 TYPICAL 3.0 2.5 MINIMUM 2.0 1.5 1 INPUT VOLTAGE (V) Switch Voltage Drop 700 600 500 400 ...
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... RUN/SS Pin Current 2 RUN/SS PIN VOLTAGE (V) 1912 G13 Error Amp Output Current –200 –100 0 100 200 FB PIN ERROR VOLTAGE (V) 1912 G16 LT1912 500 600 700 800 900 1912 G11 1912 G14 1912f 5 ...
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... LT1912 TYPICAL PERFOR A CE CHARACTERISTICS V Voltages C 2.50 2.00 CURRENT LIMIT CLAMP 1.50 1.00 www.DataSheet4U.com www.DataSheet4U.com SWITCHING THRESHOLD 0.50 0 –50 – TEMPERATURE (° Switching Waveforms; Discontinuous Operation V SW 5V/DIV I L 0.5A/DIV V OUT 10mV/DIV 100 125 150 2μs/DIV V = 12V 3.3V IN OUT I = 110mA LOAD 1912 G19 T = 25° ...
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... Clock edges should have rise and fall times faster than 1μs. See synchronizing section in Applications Information. N/C (Pin 7): This pin should be tied to ground. FB (Pin 8): The LT1912 regulates the FB pin to 0.790V. Connect the feedback resistor divider tap to this pin amplifi ...
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... BD pin is connected to an external voltage higher than 3V bias power will be drawn from the external source (typically the regulated output voltage). This improves effi ciency. The RUN/SS pin is used to place the LT1912 in shutdown, disconnecting the output and reducing the input current to less than 1μA. ...
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... The reason input voltage range depends on the switching frequency is because the LT1912 switch has fi nite minimum on and off times. The switch can turn on for a minimum of ~150ns and turn off for a minimum of ~150ns. ...
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... L OUT(MAX) where I is the maximum output load current. To OUT(MAX) guarantee suffi cient output current, peak inductor current must be lower than the LT1912’s switch current limit (I The peak inductor current is ΔI L(PEAK) OUT(MAX) where I is the peak inductor current, I L(PEAK) the maximum output load current, and Δ ...
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... See AN19. Input Capacitor Bypass the input of the LT1912 circuit with a ceramic capaci- tor of X7R or X5R type. Y5V types have poor performance over temperature and applied voltage, and should not be used. A 4.7μF to 10μF ceramic capacitor is adequate to bypass the LT1912 and will easily handle the ripple current ...
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... If the )/V IN LT1912 circuit is plugged into a live supply, the input volt- age can ring to twice its nominal value, possibly exceeding the LT1912’s rating. This situation is easily avoided (see the Hot Plugging Safely section). ...
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... If the input voltage is ramped slowly, pin. Note that C ) integrates the error ampli series with C ) across the feedback divider Figure 3. Transient Load Response of the LT1912 Front Page Application as the Load Current is Stepped from 500mA to 1500mA. V LT1912 CURRENT MODE SW POWER STAGE ERROR ...
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... For example, if the synchronization signal will be 250kHz and higher, the R To assure reliable and safe operation the LT1912 will only synchronize when the output voltage is near regulation therefore necessary to choose a large enough inductor ...
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... LT1912 is absent. This may occur in battery charging ap- plications or in battery backup systems where a battery or some other supply is diode OR-ed with the LT1912’s output. If the V pin is allowed to fl oat and the RUN/SS ...
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... LFPM airfl ow, this resistance can fall by another 25%. Further increases in airfl ow will lead to lower thermal re- sistance. Because of the large output current capability of the LT1912 possible to dissipate enough heat to raise the junction temperature beyond the absolute maximum of 125°C. When operating at high ambient temperatures, the maximum load current should be derated as the ambient temperature approaches 125° ...
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... APPLICATIONS INFORMATION Power dissipation within the LT1912 can be estimated by calculating the total power loss from an effi ciency measure- ment and subtracting the catch diode loss and inductor loss. The die temperature is calculated by multiplying the LT1912 power dissipation by the thermal resistance from junction to ambient ...
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... LT1912 APPLICATIONS INFORMATION + LOW IMPEDANCE ENERGIZED 24V SUPPLY www.DataSheet4U.com www.DataSheet4U.com + + Figure 9. A Well Chosen Input Network Prevents Input Voltage Overshoot and Ensures Reliable Operation when the LT1912 is Connected to a Live Supply 18 CLOSING SWITCH SIMULATES HOT PLUG 20V/DIV V IN LT1912 4.7μ ...
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... RUN/SS BOOST ON OFF V C LT1912 R T 20k SYNC 68.1k GND 470pF f = 500kHz D: DIODES INC. DFLS240L L: TAIYO YUDEN NP06DZB4R7M V OUT BOOST L 0.47μF 6.8μ 536k FB 47μF 100k 1912 TA02 V OUT 3. 0.47μF 6.8μ 316k FB 100k 47μF 1912 TA03 LT1912 1912f 19 ...
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... LT1912 TYPICAL APPLICATIONS 4V TO 36V www.DataSheet4U.com www.DataSheet4U.com 20 2.5V Step-Down Converter RUN/SS BOOST ON OFF V C 4.7μF LT1912 R T 20k 68.1k SYNC GND 330pF f = 500kHz D1: DIODES INC. DFLS240L D2: MBR0540 L: TAIYO YUDEN NP06DZB4R7M V OUT 2. 1μF 6.8μ 215k FB 100k 47μF 1912 TA04 ...
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... ON OFF V C LT1912 4.7μ 18.2k SYNC 68.1k GND 330pF f = 500kHz D: DIODES INC. DFLS240L L: TAIYO YUDEN NP06DZB3R3M V OUT 12V 2A BD BOOST L 0.47μF 10μ 715k FB 50k 22μF 1912 TA06 V OUT 1. BOOST L 0.47μF 3.3μ 127k FB 47μF 100k 1912 TA08 LT1912 1912f 21 ...
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... LT1912 PACKAGE DESCRIPTION 3.50 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) www.DataSheet4U.com www.DataSheet4U.com 0.25 ± 0.05 2.38 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2). CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT 2. DRAWING NOT TO SCALE 3 ...
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... REF 3.00 ± 0.102 4.90 ± 0.152 (.118 ± .004) (.193 ± .006) (NOTE 0.86 1.10 (.034) (.043) REF MAX 0.17 – 0.27 0.127 ± 0.076 (.007 – .011) (.005 ± .003) 0.50 TYP MSOP (MSE) 0603 (.0197) BSC LT1912 1912f 23 ...
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... Transient Protection Linear Technology Corporation 24 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 U 1.2V Step-Down Converter OFF RUN/ LT1912 4.7μ 16.2k SYNC 68.1k GND 330pF f = 500kHz D: DIODES INC. DFLS240L L: TAIYO YUDEN NP06DZB3R3M COMMENTS V : 3.6V to 36V MicroPower Step-Down DC/ ...